How to find a ground for your amp

[Kickstand Premium Member]

So I have not seen a write up about this but if I missed it I'm sorry in advance to the mods.
Finding the proper ground IMO is one of the most overlooked area's of car audio. So many times I've seen people just put a screw in sheet metal and call it a day. So since I'm in the middle of installing a system in one of my cars I figured I would do a write on it.
Things you will need:
Multimeter
20 feet of wire give or take (nothing special just thin speaker wire will do)
I like to use a spade connector but tape will do
So start with getting however much wire it takes to reach from your battery to the trunk or wherever you are mounting your amp
https://ibb.co/bF9040W
I use a connector on the the end but I've seen people use tape. The tape tends to come off sometimes
If you have kids you can use some sort of child labor but if they are like mine they get distracted easy.
In any case attach one end of the wire to the negative lead on the battery
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Now run the wire back to where you are mounting the amp. In this case the trunk.
Attach the other end of the wire to one of the probes on a multimeter.
Make sure you tape it up so it stays.
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Now set your multimeter for continuity (the one that beeps)
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Go back to the front of the car or wherever the battery is and test it out by taking the unused probe and putting it on the negative lead of the battery
If it beeps your in business (I only have two hands so I couldn't hold the phone the multi meter and the probe but you get the point)
If it doesn't re check your connections or even the battery on the multimeter.
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Now go to where you you are mounting the amp and start touching bolts until you get a beep.
I got really lucky and got it on the first try. This doesn't happen a lot though.
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Now mine is one of the bolts that used to hold in the spare tire.
Technically the the part that is connected to the battery ground is what the bolt is threading into not the piece of sheet metal on top but for the sake of the write I will act as if its not.
So now that you have found your ground you have to remove the paint so there is a good connection
This works best IMO
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And then remove the paint
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That's it now your ready to hook your ground up.
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Sorry I screwed up posting the pictures but at least the links are there

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[LsGuy]

Good write up and is similar to what I do. However, checking continuity only tells you if you have a ground, not how good the ground is. Personally I like to check resistance instead, using the method you described. I'll check around different points until I find the best ground.

 

[Kickstand Premium Member]

Thank You
That sounds like that would be the best way to do it.
I don't have any formal schooling for any of this just what I picked up here and there but so many times I've seen people hook it up to the first bolt they can find and call it a day. That damn bolt for the seats is a common one too.
When I set things up I choose the location of the amp by where the best ground is and work around it not make the ground work around where you want your amp. 18" is all the wiggle room you should have.